Process for the simultaneous production of potassium nitrate and ammonium sulphate



June 26, 1934 A. HOLZ 1,964,158

PROCESS FOR mm SIMULTANEOUS PRODUCTION OF POTASSIUM NITRATE AND AMMONIUM SULPHATE Filed Aug. 19. 1930 a; 00 +2 HNO Solufzpn Ca (N05)2 Insoluble @50 50 Zaiz'on zmyo maso .E'z/a voraZefar crys ZaZs Ca C05 lnsoZaZie Ca C05 INVENTOR flayusiffozj 1 ATTORNE\;|

Patented June 26, 1934 UNITED STATES PROCESS FOR THE SIMULTANEOUS PRO- DUCTION OF POTASSIUM .NITRATE AMMONIUM SULPHATE August Holz, Irvington, N. J.

Application August 19,1930, Serial No. 476,449

. 3 Claims.

My method is based upon the principle that 'calcium nitrate and potassium sulphate or bisulphate react with one another to form relativel'y insoluble calcium sulphate and easily soluble potassium nitrate. This reaction is represented by the following formula: ca(uo3)2+Kzso4=caso4+2Krio3 (Formula I) While a large part of the calcium sulphate is thrown down as a precipitate, considerable calcium sulphate remains dissolved in the mother liquor and will contaminatethe potassium nitrate crystals formed in the concentration and evaporation or this mother liquor.

3 The accompanying drawing shows the flow sheet illustrating the invention. w

When using potassium bisulphate the reaction proceeds according to the following formula:

in this case even larger quantities of calcium sulphate are retained in the solution owing to the present of free sulphuric acid. I have, however, dscovered a method whereby calcium is not only removed completely but the sulphuric CaSO4+ (NHq) 2003:

CaCO3+ (NH4) 2804 (Formula 111) In the mother liquor of Formula H the free sulphuric acid is first neutralized with ammonia and then ammonia and carbon dioxide are passed into it until the calcium is removed completely into carbonate, removing this carbonate by filtra- C 4+HZSO4+2KNOJ (H) tion and evaporating the mother liquor for the (Cl. IL-9) as carbonate. The reaction in this case proceeds according to the following formula:

The process is therefore carried out as 1'01- lows: to a concentrated solution of calcium nitrate (or calcium nitrate and sodium nitrate) is added the theoretical amount of potassium sulphate or bisulphate. The resulting precipitate of calcium sulphate may then be removed by filtration.

Into the filtrate ammonia gas and carbon dioxide are then passed simultaneously until the calcium is completely precipitated as carbonate.

The precipitate of calcium carbonate is then removed by filtration and the mother liquor of potassium nitrate and ammonium sulphate is concentrated and converted into solids in the usual manner; r

If synthetic calcium nitrate is used the final products of my process are therefore 2KNO3 plus (NH4)2SO4 in the case of potassium sulphate, or 2KNO3 plus 2(NH4)2SO4 in the case of bisulphate. If. however, calcium nitrate obtained from the conversion of Chilean nitrates is used, the product naturally contains considerable sodium nitrate.

I claim:

I 1. The method which comprises treating calcium nitrate with potassium sulphate, removing the precipitated calcium sulphate by filtration and then passing into the mother liquor ammonia and carbon dioxide until all calcium is converted production of potassium nitrate and ammonium sulphate.

2. The method which comprises treating calcium nitrate with potassium sulphate, removing the precipitated calcium sulphate by filtration, passing into the liquid reaction product ammonia and'carbon dioxide under slight pressure until all the calcium is converted into carbonate, re-

moving the precipitated calcium carbonate by 111- tration and evaporating the mother liquor for potassium nitrate and ammonium sulphate.

3. The method which comprises treating calcium nitrate with potassium bisulphate, passing into the reaction product gaseous ammonia until all free acid is neutralized, then passing ammonia simultaneously with carbon dioxide into the mixture under slight pressure and continual agitation, removing the precipitated calcium carbonate by filtration and evaporating the mother liquor for U5 the production of potassium nitrateand ammonium sulphate.

. AUGUST HOLZ. 

